I'm not sure where you live but if it's anywhere near North Leicestershire there is an evening class at Rawlins College in Quorn on a Monday night. It's more like a club than a structured course. You can build pretty much anything you want within a pretty well equipped school workshop. There are three experts on hand to advise you, the main one being luthier Colin Keefe (ex-Eggle guitars, now independent). Fees are 80 odd quid for a ten week term of 2 hour sessions.
If you're interested search for "Guitar Building at Rawlins College" or drop me a PM and I'll put you in touch. They have a page on Facebook and a website afaik.
Numbers are limited obviously. Many members have been attending for years and are very knowledgeable and supportive too